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SubjectRe: [PATCH] reboot: Backup orderly_poweroff
On Mon, Jan 11, 2016 at 03:53:24PM +0530, Keerthy wrote:
> orderly_poweroff is triggered when a graceful shutdown
> of system is desired. This may be used in many critical states of the
> kernel such as when subsystems detects conditions such as critical
> temperature conditions. However, in certain conditions in system
> boot up sequences like those in the middle of driver probes being
> initiated, userspace will be unable to power off the system in a clean
> manner and leaves the system in a critical state. In cases like these,
> the /sbin/poweroff will return success (having forked off to attempt
> powering off the system. However, the system overall will fail to
> completely poweroff (since other modules will be probed) and the system
> is still functional with no userspace (since that would have shut itself
> off).
>
> However, there is no clean way of detecting such failure of userspace
> powering off the system. In such scenarios, it is necessary for a backup
> workqueue to be able to force a shutdown of the system when orderly
> shutdown is not successful after a configurable time period.

One issue below, inline.

> Signed-off-by: Keerthy <j-keerthy@ti.com>
> Suggested-by: Eduardo Valentin <edubezval@gmail.com>
> Reported-by: Nishanth Menon <nm@ti.com>
> ---
> Links to previous discussion can be found here:
>
> http://www.spinics.net/lists/linux-omap/msg124925.html
>
> Boot tested on DRA7.
>
> arch/Kconfig | 7 +++++++
> kernel/reboot.c | 23 ++++++++++++++++++-----
> 2 files changed, 25 insertions(+), 5 deletions(-)
>
> Index: linux/arch/Kconfig
> ===================================================================
> --- linux.orig/arch/Kconfig 2016-01-11 15:26:07.732173131 +0530
> +++ linux/arch/Kconfig 2016-01-11 15:26:07.728173205 +0530
> @@ -37,6 +37,18 @@
> def_bool y
> depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
>
> +config SHUTDOWN_BACKUP_DELAY_MS
> + int "Backup shutdown delay in milli-seconds"
> + default 0

With no dependencies, as far as I can tell this will always get defined
with a value, defaulting to 0. (I don't know of any special cases in
Kconfig for an int value of 0.) Thus, in the code below...

> --- linux.orig/kernel/reboot.c 2016-01-11 15:26:07.732173131 +0530
> +++ linux/kernel/reboot.c 2016-01-11 15:38:33.502341511 +0530
> @@ -424,6 +424,38 @@
> return ret;
> }
>
> +#ifdef CONFIG_SHUTDOWN_BACKUP_DELAY_MS

...this should use #if, not #ifdef. Otherwise this code will get
compiled into every kernel.

- Josh Triplett

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